push_to_insights.sh

remove beta build flows & branch references

webpack.config.js

this file references preview or beta (interchangeably), in:

• chromeTemplate
• output.publicPath
• devServer.historyApiFallback

package.json

clean up the BETA env-var (this also touches other files in the sentry-release flow, like sentry-env.sh)

don't think we can do this, as long as the FE build-container still builds twice and exposes BETA.
cleaning up this check in our code would result in building & publishing sourcemaps twice for each build

i verified this with Victor M, to be sure. i might open a PR to RH-Insights, with a change to universal-build, at some point.